Checking circuit



April 28, 1959 M. YOUNG 2,884,487

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'rrToRNEY United States `Patetfit n l 2,884,487 cHEcKlNG CIRCUIT Paul M.,Young, Pleasant Valley, N.Y., assignorto Intervnational Business Machines Corporation, New York, NX., a corporation of New York Application December 30, 1955, Serial No. 556,505

1 Claim. (Cl. 178-23) This invention relates to a tape reading machine and more particularly to a mechanism for checking the codes in a tape being read by said machine in tape read cycles.

4There is a need in the art for a mechanism for determining the correctness of codes themselves as well as the interpretation of the codes as they are read in the tape, accordingly, it is a first object of this invention to provide an improved tape code checking device.

`It is a further object of this invention to provide a mechanism for checking the accuracy of. the codes read by a tape reader.

It is a still further object of this invention to provide a mechanism for checking the correct operation of a tape reader.

In some operations, it is desirable to check a tape for an odd number of codes in a cycle while in still other operations, it is desirable to check a tape for an even number of codes in a cycle, and accordingly, it is a still further object of this invention to provide an improved mechanism for checking either odd or even codes in a tapete-ader.

Other objects of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings, which disclose, by Way of example, the principle of the invention and the best mode, which has been contemplated, of applying that principle.

In the drawings:

Fig. 1 is a side elevation of a tape reader.

Fig. 2 is a wiring diagram representing the operation of the checking circuit of the tape reader.

Fig. 3 is a timing chart.

Fig. 4 is a sample of the tape with an odd number ofholcs in a code.

Fig. 5 is a portion of tape with an even number of holes in a code.

Briefly, this invention relates to an improved mechanism and control circuitry for use with a paper tape reader whereby each tape code is analyzed by sending a pulse through a checking network. The machine is stopped unless a proper code has been read.

Reference is made to Fig. l of the drawing which illustrates one view of a paper tape reader shown and described completely in U.S. Patent 2,637,399. Briefly, the tape reader is equipped with a cam which is cyclically driven rwhen the tape reader is turned on. Cam 2 acts on cam arm 4, via spring 5 and cam follower 6 to rock about its support pin 8. Actually, support arm 4 comprises two parallel spaced apart actuator arms` 9 interconnected for corresponding rocking motion in response to the cam imparted motion of cam arm 4 via a transverse bail 10. The arms 9 are each equipped with studs 14 which are 'movablein response to the operation of cam 2 from the solid line position to the dotted line position.

In the tape reader, a plurality of pins 16 (one for each tape row) are mounted for sliding movement in a reader pin support `18. Each reader pin is equipped with a notch 20 engageable with a corresponding pin driver arm ICS 2 22. Each pin driver arm 22, in turn, carries a spring 24, which is hooked on the frame and passes under pin 8 to engage a pin 26 on the tape driver arm 22. With this arrangement, when bail 10 is removed, via the rocking of cam arm 4, the spring 24 acting through pin 26 will l drive the read pin 16 down towards a taperead station 28. Paper tape 29 is passed in columnar steps across` the tape read station 28 in response to the movement of pin wheel 30 which is cyclically driven by a cam operated mechanism, not shown. If the column of tape 29 at the read station 28 has perforations in it, then the pin 16 assigned to a particular tape row can pass through the perforation in that row. In this respect, the tension of the spring 24 is suicient to move the pin 16 down, but

not enough to perforate the tape, if a hole is not already there.

If a pin 16 enters the tape, a blocking ear 32 on the pin drive arm 22 is moved out of the path of a complementary shoulder 33 on the contact lever 34. A plurality of contact levers 34 (one for each pin 16) are supported for rocking movement about a pin 36. Each contact lever 34 is interconnected with a corresponding spring contact 38 in a manner to bias open a set of contacts 40. When a contact lever is free e.g. when blocking ear 32 is removed from shoulder 33, spring contact 38 acts to close contacts 40. On a return stroke, e.g. when the bail 10 lifts the pin drive arms 22, stud 14 is wedged between rollers 42, which acting via hails 44, restore all the contact levers to their Fig. l position.

In essence then, on each tape read cycle, which is measured by one revolution of the cam 2, pins 16 are spring driven down seeking apertures in the tape during one portion of a cycle, and for each pin that reads. a hole in the tape, a corresponding contact 40 is closed. On the remainder of the cycle, the read pins are restored and all contacts 40 are opened.

The closing of contacts 40 in response to a pin reading a tape hole is utilized to establish a check circuit for 1 relays 46 bear corresponding tape code designations Each relay 46 has plural contact points 48 which are used in a check circuit, and the tape code contacts 40, relays 46 and their contacts 48 are listed as follows:

Tape Row Code Contacts Relays Contact Points 46EL SEL-48 1 through 2. 46-X X-48 l through 8. 46-0 0-48 1 through 5.

In essence, it will be understoodvthat for each code a corresponding relay 46 will be energized to close the n corresponding relay contacts 48.

The cams P2, P5, P6 are closed every tape read cycle in accordance with the sequencev chart of Fig. 3, and atl one portion of a cycle, a pulse is sent through contacts 48 when cam Contact P5 closes. If the contacts 48 satisfy a predetermined pattern network, then code check relay 50 will be energized. In turn, the code check relay 50 has a hold circuit through its own contact point at cam P2 time.

Reference is now made to the sequence chart of Fig. 3 wherein it is shown that the pulse throughmthe reader Patented Apr. 2,8, 19.5 9`y i cmacf 4o during cam P6 throughthe P 2 will Stop.

.selectioncontrol plugr SZis provided in the contact 4 8 the pulse fothe`50`liold'cois continuous,exceptduring P-S time. Accordingly, pickedup by a pulse atcamfll-S time passingthrough the Cli'cktig stwcrk, then if L? prefiera-.S finie, voil? if ,the code check relay `t) is 1,11' ,win be ,heid up iby a puls.'

asemeja 1 thermorgfthe check relay 4has a normallybpencontact 5 0- 2 ina run .relay Slcircuit, therefore, if a pulse is not ayailable through relay 5 041 (will dro c` eckingl'circuit whereby the checking circuit maybe selectively changed for either odd, or even checking, i.e.

foreitheran 'odd oneven' number of taperholes `in any tape column'. Selection control plug SZeOmprises apair the checlnng circuit atevery ,P-Sftirne, p out opening Sil-2 and the machine pairofinputhuss, evn hasse-rand @da nubes-2. Hub

54-1`is Wired toa contact 4-48-3 while hub-54`2 'is wiredto contact 4- 4831 The hub 56-1 is .wiredto a contact2- 48-1 whileihub 5,62 vis wired to contact 2- 48-21 With Vthe selector control mechanism 52 cross wired, .as

shownin solid lines of Fig. `2, an even hole check is. provided, while if selectorcontrolmechanism 52` is cross Wiredas shown in dotted lines, an odd hole check circuit isy provided.

circuit In the operation'of thismechanism, astart key S8 i s` closed to send a which `willbe held through P-2 cam contact, normally closed, and through contact 50-1 normally open, now closed. Simultaneously,

pulse to the code checkrelay 50-`P a pulse is available through rectier 53 to energize therun relay 51, which will beheldy up vthrough relay -point 50-2. The reader will start oper,- ating and the iirsttape columnwill be read. t

Reference is now made to` Fig. 4, wherein each tape column has anodd number of holes.` letter A is represented bythe holes l, 0 withreference, to Fig.` 2, when that rst read station 28, the pins 1 6 should pass through `the 1 hole, `the 0 `hole and the X `holeQwher'eupon at P6 time, `a pulse is to be available through 40-1 contact, 44)- 0 contact and 40-X contact to energize the 46-1, 446-0, 46-X relays. Then, at P-S time, `a

and X, therefore,

For example, the t pulse is available through tape columnisin i contact 0-48-3 normally open, now closed; through the i contact 0-.48-2 normally open, now closed, through now closed to the X-48- 1 Contact 0-48-1 normally open, normally open, now closedjthrough `the X-48-4 contact normally operi, now closed, through the X-48-6 contact normally open, now closed; through the Q-484 contact normally open, now closed to the EL-48- 2 normallyclo'sed Contact to the CK-482 normally closed` contact to the 4 48-2 normally closed contact closed contact to the hub 54-2 to the 4-48l4 normally through the dotted wire to the 56e2 .hub .then up `to 2-48- 2`normally closed corn` mally'closed'contact, to the 8 48-'3 normally closed con'- tact, .tothe 8e48-5 normally closedcontact gto energize the codecheck relay 50. `It will be found thatvany odd numbery of holes which form part of thccode willenergie the' relays 46 in such a manner as'k to lform apa'th throughthe contacts 48 (and Then a pulse will be available through the P-S Contact through0448-3 normally closed,`:0-"4 8-4 normallyjclose` 0-4815 normally yclosed to' the `XMS-Tno'rrnally closed pins 16 willzread the `2 andy 4 tape holes.

check.k i 1 `Ylhilefthere have Abeen shown and described and pointed out the fundamentalnovel features ofthe invention as t applied to `a ,preferred embodiment, it `will be understood` i solid line wiretohuh 56-2; mally open, now closed; therifto the contact12-48-3 nor` the ends o f, cam 2 time. A `With ,this .mechanism ofcrcuitry, it is )obvious that either an odd or aneven bit vcode/can be checked to de-` termine whetherthe proper ni'unlxex`- of holes have been `read `at the tape 'read station andwhether` or not the tape contains the that various, omissions, andk substitutions and changes .the form and `details ofthe device illustrated and in its be made `by those skilled in the art withy out departing from `the spirit of the invention. It is the ted by the operation may intention, therefore, to be limited only as indica scope ofthe followingjclaims. 1 i

What is claimedis: i A device for detecting `improperly coded character `groupsincoded tapes .Containing detain the form of character groups in columns spacedalong the `length of the f tape, each character grouphavingfa plurality of bit posi`` marked to be representative vof tions which are selectively a codedcharacter kof data, and aparty bitposition, which is lselectively marked in odd-parity .tapes to' cause the aggregate number ofmarksy in each properly lcoded character group to be odd, or thecoverse for evenaparity tapes, l said bit positions rbeing in respective rows along thelength of the tape, comprising; selectively operable rn'eans toi" reading all the bits forming a character group `during a a plurality of pattern relays associated i respectively with the bit `positionsfto be read from .the tape, said relays being simultaneously operable in response tape columncycle;

to marks being read in the respectively associated bit positions; code check relay means comprising a 'switchelelcf s tive, when closed, to'operategsaidreading means; acirc'uit network comprising a rst maze o f pattern relay contacts,

associatedwith certainof `said pattern relays,M a second i `maze of patterny relay contacts, associated with rthe re- `maining pattern relays, and oddyeven parity. switchingy i Y means,` havingk odd input and'even input-said first maze being arranged to provide a circuit path to` said'odd output terminal in response to an odd number 1of its associated pattern relays beingenergized,"y and to saideven output terminal in're` n four terminals,` bdd-output; reven output;

sponsetov an even lnumberof itsiassoeiatedpattern relays ranged to connect' the co'clelcheclrl Lrelayfto said odd input terminal in response to an ddnumber of its associated pattern relays being energizd,`a n d to said `even input ter`y minal'in responseto anyen number of/its associated patt `ternrelays being energizedf-whereby theroperator, by

settingthe switching means to `connectoddoutput to odd input and even output References Citedinthe le of'this patent` UNITED STATES PAT-attrs l proper numberofholesto satisfy the code to even input s etsjthe device for even parity, andbyset'ting the switching means to connect t odd terminals tof eyen termihalssetsfjthe device for odd parjty and assuming the tape' 

